TM 1-1520-238-232-312Change 42.88.ROTOR SUPPORT MAST SUPPORT BASE REMOVAL/INSTALLATION  continuedWARNINGThe surface of the transmission cover and the mast base with the geared curvic coupling areprecise surfaces. Normal handling of aluminum parts do not apply. Do not abrade surfaces ofthe curvic teeth over any extensive area. Small material movements can cause the curvicsurfaces to fail to mesh. If the curvic shows impact damage as would be caused by tool impactor rough handling, remove any displaced metal to the surface. If the surface is corroded, sendthe parts to depot maintenance. Mast base curvic coupling must be entirely free of debris,displaced metal, and burrs.NOTEPosition mast base on struts so that one mixer pivot support faces forward, and the other supportfaces right side of helicopter.Nuts may be reused if run-on torque exceeds 50 INCH-POUNDS.GO TO NEXT PAGE